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The History of Cortisol

Cortisol's story began in the 1930s at the Mayo Clinic, where American biochemist Edward Calvin Kendall isolated several distinct hormone compounds from the adrenal cortex, the outer layer of the adrenal glands sitting atop each kidney in the human body. Around the same time, Polish-Swiss chemist Tadeusz Reichstein independently isolated closely related compounds in his own laboratory across the ocean in Switzerland, entirely unaware of Kendall's parallel progress at the time. The discovery's true significance became dramatically clear in 1948, when Mayo Clinic physician Philip Hench administered one of these compounds, cortisone, to a patient severely disabled by rheumatoid arthritis and watched her regain mobility within just a few days, a result striking enough to make front-page news around the entire world almost overnight.

What Cortisol Actually Is

Cortisol is the body's primary stress hormone, produced by the adrenal cortex under close direction from the brain's hypothalamus and pituitary gland working together as a single coordinated regulatory system. It helps regulate blood sugar by prompting the liver to release stored glucose, suppresses inflammation and immune activity throughout the entire body, and follows a distinct daily rhythm, rising sharply in the early morning to help a person wake up and gradually falling throughout the day to its lowest point at night before sleep finally begins. This natural rhythm is precisely why doctors typically specify exactly when a cortisol blood sample should be drawn, since the same person's result can look completely different depending on the exact time of day it's collected from them that day.

How Cortisol Is Measured

Cortisol is most commonly measured in blood using chemiluminescent immunoassays, in which antibodies designed to bind cortisol trigger a light-emitting reaction whose intensity a machine can precisely quantify within a fairly short period of time each and every time. Saliva testing has also become increasingly popular in recent years because it's simple to collect at home and closely reflects the biologically active, unbound form of the hormone circulating at that particular moment in the body. For certain diagnostic situations, such as suspected Cushing's syndrome, doctors instead order a 24-hour urine collection, measuring the total amount of free cortisol the body has cleared over an entire day rather than relying on just a single snapshot moment in time alone entirely.

Scientists Behind the Science

Edward Calvin Kendall's painstaking isolation work at the Mayo Clinic throughout the 1930s laid the essential chemical groundwork for everything that followed afterward in this entire field of endocrinology. Tadeusz Reichstein's parallel, independent research in Switzerland confirmed and extended those same findings from an entirely different scientific angle at roughly the very same time in history. Philip Hench's dramatic 1948 clinical demonstration proved beyond any doubt that these adrenal compounds had genuine, powerful therapeutic value, not just theoretical biochemical interest confined to a research laboratory somewhere far away. All three scientists jointly received the 1950 Nobel Prize in Physiology or Medicine for this combined body of work, one of the fastest-recognized Nobel achievements in the hormone's short but remarkably consequential scientific history to date and beyond.